This invention relates to power supplies for image tubes, and more particularly, relates to power supplies for image tubes which utilize microchannel plate (MCP) electron multipliers.
Image intensifier tubes are used to help an observer see objects under light conditions which would normally preclude vision, i.e., in night vision systems. In general, image intensifier tubes use some type of photocathode upon which the incident light is focussed to generate electrons. These electrons are then accelerated and cascaded by various means and impact a phosphorus screen which via a lens depicts the resulting intensified image. Depending upon the amount of voltage applied to the electrons and the amount of electron cascading (or amplification) the intensity of a single incident photon is increased significantly allowing for vision under very low light conditions. However, to prevent the image on the screen from becoming too bright for human comfort, various circuits have been used to control the brightness or gain of the intensifier tube.
However, it is difficult to have a power supply for an image intensifier that includes these features in an economical and reliable circuit. In addition, it is desirable that the voltages applied to various portions of the image intensifier tube be adjustable to provide for adjustments in the onset of the automatic brightness control. Further, it is desirable to include as many of the circuit elements as possible associated with such a power supply in a single integrated chip. The power supply of the present invention fulfills all these unmet needs.
These and other limitations and disadvantages of the prior art are overcome by the present invention, however, and an improved power supply is provided for an image intensifier tube.